As described in U.S. Patent Application Publ. No. 20170013781 to Flickinger, which is incorporated by reference herein in its entirety and for all purposes, an agricultural harvester known as a “combine” is historically termed such because it combines multiple harvesting functions with a single harvesting unit, such as picking, threshing, separating and cleaning. A combine includes a header, which removes the crop from a field, and a feeder housing which transports the crop matter into a rotary threshing and separating system. Conventional components of a combine harvester are shown in that patent application publication.
The rotary threshing and separating system includes one or more rotors which extend axially (front to rear) or transversely within the body of the combine, and which is partially or fully surrounded by a perforated concave. The crop material is threshed and separated by the rotation of the rotor within the concave.
As is described in U.S. Pat. No. 8,133,101, which is also incorporated by reference herein in its entirety and for all purposes, because combine harvesters are utilized to harvest a wide variety of different crops and must function properly in many different operating conditions, it is important to be able to conveniently and accurately adjust the running clearance in the region between the one or more rotors and concave to best accommodate these variables. U.S. Pat. No. 8,133,101 describes one device for adjusting the clearance between the rotors and the concave.
Many concaves are pivotable about a single pivot point to adjust the clearance between the rotors and the concave. As combine capacity has grown, so has concave wrap (i.e., the arc measure of the concave about the rotor). The concave wrap shown in FIGS. 2A-2D is about 180 degrees, for example. The increase in concave wrap coupled with the limited ability of the aforementioned concaves to pivot about a single fixed pivot point has resulted in an inconsistent concave clearance profile as the clearance between the rotors and the concave is adjusted for various crops. Such geometry forces a larger change in clearance at the bottom of the concave relative to the sides of the concave, which forces the shape profile away from the traditional wedge profile that is desirable in the art.
Improvements in devices for adjusting the clearance between the concave and the rotor are continuously sought in the interest of improving crop processing efficiency.